Color photography



Sept. 25, 1945. J. A. BALL ETAL 2,385;599

COLOR PHOTOGRAPHY Filed March 15, 1945 2 Sheets-Sheet l (BLUEPECORDapzzlvpzcozp pzopzcopm o o c a o c' c c:

CARBON TISSUES 20 YELLOW mAazmrza ZZ BLUE-GREEN --24 Sept. 25, 1945. J.A. BALL ETAL COLOR PHOTOGRAPHY 2 Sheets-Sheet 2 Filed March 15 1945 FJ ZPatented Sept. 25, 1945 COLOR PHOTOGRAPHY Joseph Arthur Ball, LosAngeles, and Lawrence Plotin, North Hollywood, Calif., assignors to MaxMcGraw, doing business as McGraw Colorgraph Company, Burbank, Calif.

Application March 15, 1943, Serial No. 479,210-

4 Claims.

y will be apparent that essentially the same process,

with minor variations, may be used for producing transparencies to beviewed by transmitted light.

One of the objects of the present invention is to provide an improvedprocess for forming photographic color prints which is particularly welladapted for the production of commercial portraits.

Still another object is to provide an improved process for producingpermanent color prints photographically.

Yet another object of the present invention is to provide a novelphotographic color print process by the use of which natural colorprints can be produced at extremely low cost while maintaining highstandards as to quality of reproduction.

Another additional object of the present invention is to provide a lowcost color print process which retains the advantages associated withcolor separation negatives.

Still another object of the present invention is to provide a processfor forming color prints from color separation negatives which does notrequire manipulation by a skilled operator.

Still another object of the present invention is to provide a colorprinting process for forming color prints of the carbon type which isparticularly well adapted. for use with mechanical registration schemes.The term carbon" as here used will be explained presently.

Yet another object of the present invention is to provide an improvedcarbon type color print process.

Another object of the present invention is to provide a novel method forpracticing a carbon type color process which insures the registration ofthe finally assembled images without the necessity for skilled manualmanipulation as ordinarily practiced.

An additional object of the present invention is to provide a novelprocess for sensitizing, eitposing, washing, and assembling a pluralityof bichromated gelatin images which insures the final registration ofthe several images even though the images are repeatedly passed throughsoaking and drying steps.

Other objects and advantages will become apparent from the followingdescription of a preferred embodiment of our invention illustrated inthe accompanying drawings.

In the drawings in which similar characters of reference refer tosimilar parts throughout the several views:

Fig. 1 diagrammatically illustrates a set of color separation negatives,from which a color print is to be prepared;

Fig. 2 is a diagrammatic illustration of three sheets of carbon tissueupon which color images are to be prepared corresponding to thenegatives of Fig. 1;

Fig. 3 illustrates the act of placing one of the sheets of-carbon tissueupon a transparent base rior to its exposure;

Fig. 4 may be considered as an illustration of the step of exposing thecarbon tissue;

Fig. 5 is a perspective view of a portion of a transparent support witha relief color image adhering thereto;

Fig. 6 is a plan view of a screen-covered frame upon which a temporaryimagesupporting surface is formed;

Fig. 7 illustrates in plan the temporary support as formed from thescreen-covered frame illustrated in Fig. 6;

Fig. 8 illustrates a step in the process wherein one of the reliefimages mounted upon a plastic sheet is secured to the temporary supportillustrated in Fig. 7;

Fig. 9 illustrates thetemporary support with a relief image thereonafter removal of the plastic sheet; and

Fig. 10 may be considered as a plan view of the final product of thepresent process.

Most color printing processes of a photographic nature fall into one offour general classifications. One of these consists in preparing aspecial printing paper upon which a color print may be formed by asingle exposure, dyes being formed or destroyed in the print bysubsequent chemical treatment. Another process comprises the preparationof separate pigmented gelatin images in a manner to be described ingreater detail presently, these images being later assembled upon asupport to produce the final print. A third, or dye imbibition process,consists in forming separate dye absorbing printers from which dyes aretransferred one at a time to a print surface. In the fourth process,dyed images are formed in thin sheets of Cellophane or collodion, thesesheets 1:531; being stacked upon a support to produce the P Theformation of color prints by the first above mentioned type of process,that is, by a single exposure; is subject to several rather seriousdisadvantages which render this process unacceptable for portrait use.One of these disadvantages is that the dyes used in the print mustnecessarily be comparatively unstable, since they must be easily formedor destroyed chemically. Thus a print produced by such a process has acomparatively short life before bleaching of one or more of the dyesupsets the color balance. Portraits therefore cannot be made which willlast a generation, this period generally being considered to be theminimum satisfactory life of a commercial portrait.

Prints made by the inbibition process, or the dyed Cellophane orcollodion processes, also bleach, since no soluble dyes are permanent.

On the other hand, printing processes which produce the final product bysuperposing a plurality of color images formed by the selectivehardening of pigmented gelatin can have great permanence. This isbecause the pigments used in pigmented gelatin need not be'soluble orchemically active, and thus can be chosen with great permanence in mind.Color portraits therefore can be produced by pigmented gelatin processeswhich will last for many years without noticeable change.

In addition to the above considerations directed to the printingprocesses per se, it is an axiom of portrait photography that portraitsmust be retouched, and frequently such retouching must be carried outrather extensively. Therefore, any photographic process which does notlend itself well to retouching cannot be used for forming commerciallyacceptable portraits. For this reason a portrait process should usecolor separation negatives, since a set of separation negatives canquite easily be retouched without disturbing its balance. This islargely because necessary retouching consists usually in the removal ofblemishes which show up as lines or spots on all of the negatives in theset. In most instances the retouching can be considered satisfactory ifthe density of each of the negatives where the blemishes appear isreduced or increased to that of the adjacent negative area. As a rule,most retouchers who are skilled in black and white work have littledifficulty in adequately retouching color separation negatives.

In view of the above, it is evident that a color process, especiallywhen used for producing portraits, should start with color separationnegatives and should preferably be of the pigmented gelatin type or atleast of some type which permits the use of permanent pigment which arenot required to enter into the process chemically and which need not besoluble.

With the above considerations in mind, the present process, whichalthough it is universally applicable has nevertheless been developedespecially for the low-cost production of color portraits, starts withcolor separation negatives and uses pigmented gelatin images. In generalthe present process may be considered as a Carbon type process, in thatseparate color images are formed by washing exposed bichromatedpigmented gelatin in hot water, these images later being superposed toproduce the final print.

The color separation negatives used as the starting point in the presentprocess may be formed in any of anumber of ways, the best for commercialpurposes probably being to expose the negatives in a so-called one-shotcamera in which the light beam is-split within the camera into threeparts, each of these parts passing to a separate negative throughcolor-separation filters.

- Another method for forming color separation negatives is by theso-called tri-pack process, in which images are formed in the emulsionsof three separate films placed together as a pack in a camera, theemulsion in the foremost film being sensitive to blue light only, whilethe second film's emulsion is sensitive to blue and green, a filterlayer being interposed between the first and second emulsions to filterout the blue light. After passing through the first and second films,the remaining light passes through a third filter layer which takes outall but the red light, and into a panchromatic emulsion which forms thered color record. The three films after development therefore serve ascolor separation negatives, the foremost or colorblind emulsion servingas the blue record, the intermediate orthochromatic emulsion forming thegreen record, while the rearward or panchromatic emulsion serves as thered record. One serious disadvantage of this process for the formationof color separation negatives is that some diffusion will be found inthe orthochromatic emulsion and considerable diffusion in thepanchromatic emulsion. This is noticeable in the final print, not onlyby a general softening of the image, but also by a colored haze wherelightly and strongly colored areas adjoin.

A third method which may be used for forming color separation negativesis to expose three films successively in a sliding back camera withfilters placed in front of the films or before the camera lens. Thismethod is comparatively simple in operation, its principal disadvantagebeing that the subject may move between successive exposures, thusthrowing the color records out of register.

Another commonly used method is to take the picture originally upon aspecial film which is processed to produce a colored transparency, andthen form color separation negatives from the transparency.

By whatever manner the color separation negatives are formed, such a setof negatives is used in producing a print by the present process, theparticular method of forming the color separation negatives not being afeature of the present invention.

Carbon processes for producing color prints from color separationnegatives depend upon the phenomenon that soft gelatin, if it issensitized in a bichromate solution and subsequently dried, isproportionately hardened by light. A an example, if a sheet of papercoated with dried bichromated soft gelatin is exposed beneath anegative, the gelatin will be hardened in the lighter negative areaswhereas less hardening will take place in the darker negative areas. Ifthe gelatin surface is subsequently supported upon a Cellu-' loid sheetand is washed in hot water, the soft gelatin will be washed away whilethe hard gelatin will remain. If the gelatin has been evenly pigmented,it will be apparent that the resulting distribution of pigment will bethe same as the distribution of the remaining gelatin. This processacquired the name Carbon? during the early history of photographybecause it was first used with finely divided carbon as the pigment forproducing black and white prints of great permanence, some examples ofthis early work still being in good condition at the present time.

The classic Carbon color process as heretofore practiced is carried outin the followin manner: Each of three different colored sheets of carbontissue, which are made up of a paper backing aseuee coated with softgelatin containing the appropriate pigment mixed therewith, issensitized in the dark or nonactinic light in a bichromate sensitizingbath. After the sheets have become thoroughly soaked they are squeegeedwith their gelatin surfaces in contact with ferrotype tins and are setaside to dry. After the sheets have dried and have popped off the tins,the drying taking place in the dark or in nonactinic light, each of thesheets is exposed beneath its appropriate color separation negative, theyellow sheet being printed through the blue record, the magenta sheetthrough the green record, and the bluegreen sheet through the redrecord.

The hardening brought about by exposure to light takes place upon thesurface of the gelatin farthest removed from the paper backing. sincethis is the surface where the light enters. Therefore the sheets cannotbe washed in hot water until some support has been provided for thehardened image. Such a support is provided in the following manner: Eachof the sheets is soaked in cold water and is then squeegeed with itsgelatin surface in contact with a sheet of Celluloid. The paper backingand soft gelatin are then washed away with hot water so as to leave thethree pigmented relief images each attached to a Celluloid support.

These separate images are then assembled upon a temporary support. Thetemporary support comprises a sheet of porous paper coated with softgelatin. Usually this sheet. is made quite pliable to aid in registry,as will become apparent presently. The temporary support is soaked incold water, as is one of the Celluloids bearing a hardened gelatinimage. The Celluloid sheet is then placed with the image in contact withthe gelatin surface of the temporary support, and the two sheets aresqueegeed together. The assembly is then set aside to dry, the waterevaporating from the back surface of the porous paper sheet, so as toestablish a firm bond between the soft gelatin of the temporary supportand the hard gelatin of the relief image. After the assembly has becomedry the sheet of Celluloid is peeled away from the temporary support,thus leaving the relief image attached to the soft gelatin surface ofthe temporary support.

The temporary support with one of the relief images thereon is thensoaked in cold water as is a second of the relief images upon itsCelluloid support. The relief image upon the Celluloid support is thenplaced over the relief image upon the temporary support in properregistry,

registry being obtained visually by the operator looking through theCelluloid sheet while stretching the temporary support differentially soas to bring the two images into proper relation, After the two imagesare in proper registry the sheets are squeegeed together and set asideto dry. After drying, the second sheet of Celluloid is peeled away fromits relief image, thus leaving the temporary support with two colorimages thereon.

The temporary support is once more soaked in cold water, as is the thirdrelief image, and the third relief image is placed upon the temporarysupport in proper registry with the two images thereon by againdifferentially stretching the temporary support to produce properregistry. The assembly is once more dried, and the third sheet ofCelluloid is peeled away to leave the temporary support with the threeimages thereon.

A permanent support is then provided, the

permanent support comprising a sheet of paper or other material coatedwith a layer of hard gelatin. This permanent supportiis soaked in water,as is the temporary support, and the two supports are then squeegeedtogether with their gelatin surfaces in contact, thus establishing anadhesive bond between the gelatin images and the permanent support.-'The temporary support paper and its soft gelatin coating are then washedaway in hot water to leave the relief image upon the permanent support.The permanent support is then dried to produce the final picture.

Prints produced by the above described Carbon process are comparativelyexpensive, principally because the carbon tissues shrink and expanddifferentially after they have been exposedand before they are attachedto the Celluloid supports. That is, after the carbon tissue has beenexposed it is soaked in water and squeegeed in contact with theCelluloid support. The watersoaking step softens the paper and producesuncontrollable distortion of the image thereon.

When it is subsequently desired to register three of these images, it isapparent that this registry cannot be accomplished excepting bydifferentially stretching the images relative to each other. Thisregistration step must be accomplished visually by a skilled operatorwho sees the images while looking through the Celluloid sheet. It is anextremely painstaking and expensive operation. This difllculty cannot beovercome by the use of a mechanical registration expedient, because theproblem is not one of registering identical images but is one ofregistering three images which are distorted relative to each other.

In carrying out the present process the three color separation negativesillustrated in Fig. 1 are not printed directly upon the carbon tissuesillustrated in Fig. 2 and indicated by the numerals 20, 22 and 24 whichindicate respectively the yellow, or as it is sometimes termed, theminus blue tissue, the magenta or minus green tissue, and the blue-greenor minus red tissue. Instead, each of these tissues is taken intononactinic light where it is soaked in a bichromate sensitizing bath,which may be considered as identical to that used in carrying out theclassic Carbon process excepting that a small amount of glycerin ordiethyleneglycol is added to the sensitizing solution as a tackinessproducing agent. A typical sensitizing bath may comprise potassiumbichromate 3 to 6%, glycerin 'or diethyleneglycol about 5%, the balancewater. After soaking, each of the tissues is squeegeed with its gelatinsurface in contact with a sheet of smooth, clear, transparent plasticmaterial 25, as seen in Fig. 3. "Vinylite has been found to be welladapted to this purpose.

The sheets are then dried to remove excessive moisture, but instead ofbeing dried to the point where they will popoff a ferrotype tin as isdone in performing the Carbon process by prior known methods, they arepermitted to retain a slight amount of moisture. We have found that goodresults are obtained by drying to equilibrium in an atmosphere ofapproximately to relative humidity. When dried in such an atmospherewhen a small amount of glycerin has been added to the sensitizing bath,the soft gelatin adheres to the plastic sheet sufliciently to maintaingood optical contact betweenthese surfaces and avoid accidentalseparation. Further, we have found that at this humidity, bi-

4 assasoo chromated gelatin approxii'n ately its optimum opticalsensitivity.

Each of the carbon tissues is then exposed beneath its appropriatenegative, Fig. 4, either by contact or projection printing, in suchmanner that the light which exposes the sensitized gelatin passesthrough-the plastic sheet. The gelatin is therefore selectively hardenedupon the surface which is already in contact with the plastic supportsheet. The assemblies are then washed in hot water to remove the paperbacking and the unhardened gelatin, thus leaving the pigmented reliefimages 28 upon the three plastic sheets as shown in Fig. 5.

The three color images have therefore been obtained upon three plasticsheets without the possibility of differential shrinkage or expansion ofthe carbon tissues bringing about distortion oi the images. Further,these images can be located relative to each other upon a definiteportion of the plastic sheets by any suitable mechanical registrationscheme which will insure the three negatives always having the samelocation in the projector or contact printing frame,

and which further will insure that the three plastic sheets will beproperly registered during the printing step. If such a mechanicalregistration scheme is used, it is a simple step to insure the threeimages being. properly registered relative to parent that the repeatedsoakings and dryings of the temporary support paper necessary toaccomplish the transfer of the three images to such a temporary supportmay cause considerable dislocation of the images because of differentialshrinkage and expansion of the temporary support paper betweensuccessive registration steps. Therefore, registering the relief imagesrelative to a temporary support of this type by mechanical means willnot insure registration of the images, unless the picture is so smallthat differential dimensional changes do not become apparent.

Therefore a novel temporary support is used which does not stretch orcontract with repeated .wettings and dryings but which neverthelesspermits water to be evaporated from the back surface, such evaporationbeing necessary to permit drying of the assembly, since drying cannottake place through the plastic sheet either in the classic Carbonprocess or in the present process.

This temporary support is illustrated in Figs. 6 and 7, and is describedin greater detail in the copending application of Joseph Arthur Ball,Serial No. 479,212, filed March 15, 1943, for Adhesive temporarysupports. As shown in Fig. 6, this temporary support comprises arectangular open frame 3|, much like a picture frame. The opening inthis frame is covered by a fine mesh, of the order of 230 mesh,stainless steel screen 32, stretched in place and permanently attachedtothe frame. Such a screen is unaffected by moisture and will retain itssame dimensions and shape regardless of whether it is dry or wet.Preferably the frame 3| should be formed of metal which is similarlyunaflected by moisture. To prepare this screen for use, a warm solutionof soft gelatinis flowed over its surface, the soft gelatin beingindicated by the numeral 34 in Fig. 7. The soft gelatin wi1l,not passthrough the screen, and upon standing will level itself and aftercooling will provide a smooth upper surface of the same character as thesurface provided when a gelatin layer is placed upon the ordinarily usedpaper temporary support.

After the temporary support shown in Fig. 7

has cooled and the gelatin has hardened, one of the plastic sheets issoaked in cold water, as is the temporary support, and the plastic sheetis squeegeed with its relief image in contact with the gelatin surfaceof the temporary support, a mechanical registration arrangement beingused to insure a definite location of the image upon the soft gelatinlayer 34. If desired. this registration arrangement can use the same setof holes or other registration elements in the plastic sheet as are usedin properly locating this sheet during the printing step.

The assembly is then set aside to dry after I which the plastic sheet ispeeled from the temporary support, the hardened gelatin image remainingupon the gelatin surface 34. We have found that if the carbon tissue isoriginally sensitized in a bath containing a small amount of glycerin,this peeling step can be easily accomplished even though the adhesionbetween the carbon tissue and the plastic sheet is suillcient to'providegood optical, contact and mechanical support prior to the peelingoperation. a

The second plastic sheet is then soaked in cold water, as is thetemporary support, and after the second plastic sheet has beenregistered relative to the frame 3| with its relief image in contactwith the gelatin surface 34, the plastic sheet is squeegeed against thegelatin surface and the as-- sembly is again set aside to dry, afterwhich the 40 second plastic sheet is peeled from the temporary supportleaving its relief image properly registered relative to the firstrelief image.

The temporary support is again immersed in water, as is the thirdplastic sheet, and the third relief image is transferred to the supportsurface 34 in the same manner as the first and second relief images. Theappearance of the temporary support with a plastic sheet and reliefimage thereon priorto the step of peeling the plastic sheet from thesupport, is shown in Fig. 8, while Fig. 9 illustrates the same supportwith the relief image thereon after the plastic sheet has been peeledaway. a

After the three images have been assembled upon the temporary support,th support is soaked in cold water, as is a sheet of permanent supportmaterial. This permanent support material may comprise ,a piece ofpaper, cloth, opaque white plastic, canvas or other similar base whichshould be white and which is coated with a layer of hard gelatin. Aftersoaking, the permanent support is located with its hard gelatin surfacein contact with the surface 34 of the temporary support and is squeegeedin place to bring about adhesion between the hard gelatin of thepermanent support and the relief image upon the temporary support. Thetemporary support is then turned over and is washed in hot water so asto remove the soft gelatin from the screen 32. The image is furtherwashed in warm water to remove all of the soft gelatin adhering to thepermanent noted that from the time the three exposures have been madethrough the three separation negatives until the final print has beenproduced,

no image or latent image has at any time reposed upon any support whichcan shrink or expand.

' For this reason, the images have no opportunity to become distortedand can be registered mechanically, a step which is impossible ifshrinkage or expansion of the images is permitted to take place at anypoint in the process. Further, the present process reduces the number ofsteps ordinarily necessary in the Carbon process, in

that the sensitized tissues are dried upon plastic sheets and areexposed through the plastic sheets, whereas in the ordinary Carbonprocess it is necessary that these sheets be dried upon ferrotype tins,then exposed, then soaked in water, and then secured to the plasticsheets. The steps of removing the carbon tissues from the ferrotypetins, soaking them in water and drying them upon plastic sheets, arethus eliminated from the present process.

One method of producing mechanical registration of the images comprisespunching holes in the negatives and plastic sheets, these holes beingplaced over pins to bring about proper registration. Such an arrangementis shown in Fig. 3, where it will be seen that a round hole 28 isprovided at a central point in the lower margin of the plastic sheet 25.Toward each side edge, the lower margin is also provided with asubstantially rectangular slot 21 arranged with its long dimensionparallel to the lower edge of the plastic sheet. All three of theplastic sheets used in carrying out the process, and the threenegatives, aresimilarly punched. If the negatives are to be printed byprojection, then the holes 26 and 21 will probably for convenience bespaced more closely together in the small negatives than in the largeplastic sheets 25.

In bringing about registration, the holes in the sheets are placed overpins of the type shown in Figs, 6, 7 and 8. As shown in these figures, around pin 29 is centrally located along the lower margin of thetemporary support. This pin is of such dimensions that it fits the roundhole 28 in the plastic sheet snugly, thus preventing linear movement ofthe plastic sheet relative to the frame in any direction. At each sideof the pin 29, a rectangular pin 30 is placed. The pins 30 fit the slots21 from top to bottom but are shorter than the slots. The pins 30therefore prevent rotation of the plastic sheet 25 about the central pin29.

When such a registration scheme is used, since each of the plasticsheets 25 has a set of registration openings 26 and 21, it is a simplematter to slip the openings 26 and 21 over the pins 29 and 30, and thensqueegee the sheet across the surface of the temporary support. If suchprocedure is followed, the sheet can lie upon the temporary supportinonly one position. tAlso, since all three of the sheets are similarlypunched, all three of the sheets will lie upon the surface of thetemporary support in an identical manner. Further, if the printing framein which the plastic sheets 25 are located during the printing step hasregistration pins identical to those shown in Fig. 6, so that all threeof the plastic sheets will lie in the same position in the frame duringprinting, and if all three of the color separation negatives have beenpreviously registered relative to each other and have been punched so asto have identically located regisregistered it the negative carrier hasa properly located set of registration pins.

If exposure of the carbon tissue is made by contact printing, theprinting frame will have a set of pins 28 and Ill over which theopenings in the negatives and plastic sheets will be slipped so as tolocate each negative properly relative to the corresponding plasticsheet prior to printing. It the negatives are printed by projection,then the negative carrier will have a set of pins to locate thenegatives, while the easel will have another set of pins to locate theplastic sheets 25. The enlarger should be of comparatively rigidconstruction so as to prevent movement of the negative carrier relativeto the easel. If such rigidity is provided, printing can easily beaccomplished while insuring that all of the images produced upon thecarbon tissues will be identically located relative to the registrationopenings at the margins of the plastic sheets.

Although we have described one mechanical registration scheme, it iscontemplated that other suitable registration expedients may be used ifdesired. From the above it will be apparent that the present process isof the Carbon type, and is therefore adapted to the use of permanentpigments which can be selected upon the basis of their color andpermanence alone, it not being necessary that they be produced ordestroyed chemically, or be soluble. Further, it is apparent that thepresent process, because it never requires the placement of an image orlatent image upon a stretchable or shrinkable surface, is well adaptedto use with mechanical registration schemes, thereby eliminatingcompletely the difllcult, painstaking and highly skilled operation ofvisually registering several distorted images in producing the finalpicture. Portraits or other color pictures can therefore be produced bythe present process at comparatively low cost.

Having thus described our invention, what we claim as new and useful anddesire to secure by Letters Patent of the United States is:

1. A color printing process which comprises providing a set of colorseparation negatives, providing a set of sensitized, pigmented carbontissues, providing a set of transparent plastic water impermeablesheets, securing each of said. carbon tissues with its gelatin surfacein contact with one of said plastic sheets, printing each of said carbontissues from its corresponding negative by passing light from thenegative through the plastic sheet and into the sensitized layer,developing relief images on said plastic sheets by washing, providing atemporary support consisting of a water-permeable, non-stretchable andnon shrinkable surface coated with soft gelatin, adhesively securingeach of said relief images in turn to said soft gelatin, providing ahard gelatin-coated permanent support, adhesively securing the hardgelatin surface of said permanent support to the relief images upon saidtemporary support, and separating the permanent support and the reliefimage from the temporary support to produce the final product.

2. A color printing process which comprises providing a set of colorseparation negatives, providing a set of carbon tissues, providing a setof transparent water impermeable plastic sheets, providing a bichromatesensitizing bath containing glycerin or the like, soaking each of saidcarbon tissues in the sensitizin bath and securing it with its gelatinsurface in contact with one of tration openings, the images will beperfectly said transparent plastic sheets, drying the assemblies thusproduced, printing each of said carbon tissues from its correspondingnegative by passing light from the negative through the plastic sheetand into the sensitised layer, developing relief images on said plasticsheets by washing, providing a water-permeable, nonstretchable andnon-shrinkable temporary support having a soft gelatin surface,adhesively securing each ofsaid relief images in turn to the softgelatin on said temporary support, providing a permanent support, andfinally transferring the relief images from said temporary support tosaid permanent support.

3. The method of producing carbon type photographic color prints frommechanically registered color images, which comprises providing a set ofcolor separation negatives having identically located registrationapertures in the margins thereof, providing a set of clear transparentwater impermeable plastic sheets having registration apertures locatedin the margins thereof, sensitizing a set of carbon tissues and securingeach of these tissues with its face against each of said plastic sheets,printing each 'of said negatives upon the appropriate carbonv tissuebymeans of light passed from the negative through 'the plastic sheet tothe carbon tissue, using the registration apertures in the negatives andin the plastic sheets to register each of said negatives relativeto itsplastic sheet prior to the printing step, producing relief images onsaid plasticsheets by developing said carbon tissues without removingsaid carbon tissues from said plastic sheets, assembling the reliefimages upon a water-permeable, non-stretchable a'ndnon-shrinkabletemporary support, using the registration accuse apertures in themargins of said plastic sheets for properly locating the several imagesrelative to the temporary support during the assembly operation, andfinally transferring the images from the temporary support to apermanent support.

4. The method of producing carbon type photographic color prints withoutresort to visual registration, which comprises providing a set 'ofsensitized carbon tissues, providing a set of clear, transparent waterimpermeable plastic sheets, securing the sensitized carbon tissues withtheir faces against said plastic sheets to form a substantiallynon-stretchable and non-shrinkable support for said tissuesduringexposure and development of said tissues, printing said tissues whileattached to said plastic sheets by means of light passed through theplastic sheets, developing images on said plastic sheets, mechanicallyregistering said plastic sheets relative to saidnegatives prior toprinting, providing a waterpermeable, non-stretchable and non-shrinkabletemporary support having an adhesive surface, transferrin'g the imagesone at a time from the plastic sheets to the adhesive surface of thetemporary support, mechanically registering said plastic sheets relativeto said temporary support during the transferring step so that all ofsaid images will be placed upon said temporary support in an identicallocation, adhesively securing a permanent support to the images on saidtem porary support, and finally releasing the adhesive bond between thetemporary support and the images without disturbing the adhesiveboniibetween the images and the permanent support.

JOSEPH ARTHUR BALL. LAWRENCE PLOTIN.

